As the basic physiological function of synapses, vesicle cycling involves in many aspects of process. Among them, vesicle recycling is the basis of synaptic vesicle cycling. Studies show that clathrin mediated endocytosis is a major pathway of vesicle recycling, in which Dynamin plays an important role. Dynamin is a GTPases with molecular weight of 100 kD, which acts as "scissors" in the endocytosis, separating the clathrin coated pits from membrane. It has been found that Dynamin is associated with epilepsy, Alzheimer's disease, centronuclear myopathy, and several other neurological diseases. In this paper, we discussed the structure, function and regulation of Dynamin, and reviewed recent advance in the studies on Dynamin related diseases.
Clathrin ; physiology ; Coated Pits, Cell-Membrane ; physiology ; Dynamins ; physiology ; Endocytosis ; Humans ; Synapses ; physiology ; Synaptic Transmission ; Synaptic Vesicles ; physiology

The acinic cell carcinoma (ACC) is very rare in the nasal cavity. A 57-year-old woman suffered from nasal obstruction, postnasal dripping, and hyposmia for 2 months. Rhinoscopic examination revealed a huge polypoid mass in the right inferior and anterior nasal fossa of the nasal cavity and the mass was resected. The tumor showed the classic acinar and trabecular features of ACC on light microscopic examination. The finely granular cytoplasmic granules stained with periodic acid-schiff (PAS) and diastase digested-PAS, but not with alcian blue at pH 2.5 and mucicarmine. On ultrastructural examination, tumor cells contained numerous secretory granules diagnostic of ACC.
Acinar Cells* ; Alcian Blue ; Amylases ; Carcinoma, Acinar Cell* ; Cytoplasmic Granules ; Female ; Humans ; Hydrogen-Ion Concentration ; Middle Aged ; Nasal Cavity* ; Nasal Obstruction ; Secretory Vesicles

Exosomes are nanometer sized membrane vesicles, released in the extracellular milieu following the fusion of the external membrane of multivesicular body (MVB) with plasma membrane. They perform a certain function in immune regulation. Exosomes have been shown to be released by cells of hematopoietic and non-hematopoietic origin. Tumour-derived exosomes (TEX) exist in the supernatant of tumour cells, plasma and malignant effusions of tumour patients. They contain native candidate tumour associated antigen and are capable of transferring antigens to T lymphocytes, therefore efficiently promoting cytotoxic T lymphocyte (CTL) activation and producing antitumor immunity. However, recent evidence shows that tumor exosomes may induce immunologic tolerance and even activate immunosuppression which makes tumour escape from the immune surveillance of the host immune system. In addition, tumor exosomes may mediate a growth-promoting effect on tumor cells. These discrepancies are almost certainly due to differences in the phenotype of the exosomes.
Antigen-Presenting Cells ; immunology ; Antigens, Neoplasm ; immunology ; Cytoplasmic Vesicles ; immunology ; Endosomes ; immunology ; metabolism ; Exosomes ; immunology ; Humans ; Neoplasms ; immunology ; T-Lymphocytes, Cytotoxic ; immunology ; Tumor Escape

Phospholipase D (PLD) catalyzes the hydrolysis of phosphatidylcholine to generate the lipid second messenger, phosphatidic acid. PLD is localized in most cellular organelles, where it is likely to play different roles in signal transduction. PLD1 is primarily localized in vesicular structures such as endosomes, lysosomes and autophagosomes. However, the factors defining its localization are less clear. In this study, we found that four hydrophobic residues present in the N-terminal HKD catalytic motif of PLD1, which is involved in intramolecular association, are responsible for vesicular localization. Site-directed mutagenesis of the residues dramatically disrupted vesicular localization of PLD1. Interestingly, the hydrophobic residues of PLD1 are also involved in the interruption of its nuclear localization. Mutation of the residues increased the association of PLD1 with importin-beta, which is known to mediate nuclear importation, and induced the localization of PLD1 from vesicles into the nucleus. Taken together, these data suggest that the hydrophobic amino acids involved in the interdomain association of PLD1 are required for vesicular localization and disturbance of its nuclear localization.
Amino Acid Motifs ; Amino Acid Sequence ; Amino Acids/chemistry ; Cell Nucleus/*enzymology ; Endosomes/enzymology ; HEK293 Cells ; Humans ; Hydrophobic and Hydrophilic Interactions ; Lysosomes/enzymology ; Phagosomes/enzymology ; Phospholipase D/chemistry/*metabolism ; Protein Interaction Domains and Motifs ; Protein Transport ; Transport Vesicles/*enzymology

Recently, the gene encoding clathrin assembly protein of lymphoid myeloid leukemia (CALM), which is homologous to the AP180, was cloned from rat brain, and its expression differential to AP180 was reported (Kim and Lee, 1999). This gene product promotes the polymerization of clathrin into clathrin cage and found to be a regulator in membrane trafficking between intracellular compartments in eukaryotic cells (Kim et al., 2000). In this study, we have purified the CALM protein from clathrin-coated vesicles of rat liver using the monoclonal antibody against the recombinant N-terminal region of the CALM. The coated proteins extracted from the coated vesicle fraction was further purified by multi-step procedures involving gel-filtration and ion-exchange chromatography and SDS-PAGE. The purified protein with an apparent molecular weight of 100 kD promoted the assembly of clathrin triskelia into clathrin cage. In this respect the CALM protein bears a functional resemblance to the AP180 that has been previously described.
Animal ; Clathrin/*metabolism ; Clathrin-Coated Vesicles/*chemistry ; Liver/*chemistry ; Nerve Tissue Proteins/*isolation & purification ; Phosphoproteins/*isolation & purification ; Rats

This study was carried out to investigate pathogenesis of E. coli-induced cystitis by light and electron microscopy with immunocytochemistry. A group of ICR mice was intravesically given 0.3ml of E. coli DIE 174 lysate( 1000000000/ml). Another group was given E. coli lysate after acid solution(pH 4.5) washing for 30 minutes. The urinary bladders were observed at 2 hours and 24 hours after E.coli lysate irrigation. On light microscopy, submucosal edema, congestion, and perivascular neutrophilic infiltration occurred 2 hours after E. coli lysate irrigation. The congestion and acute inflammation were more pronounced 24 hours after. In cases of acid washing and E. coli lysate irrigation, mucosal acute inflammatory infiltration with edema and congestion was marked at early stage. Necrosis of transitional cells developed with time. On immunostain for E. coli, surface of transitional cells was stained 2 hours after E. coli lysate irrigation. At 24 hours after irrigation, intercellular spaces of transitional cells were stained. In cases of acid washing and E. coli lysate irrigation, entire mucosa was stained at early stage. Electron microscopically, transitional cells revealed increase of cytoplasmic processes, enlargement of cytoplasmic vesicles, and widening of intercellular spaces. There were large amounts of various shapes of lysosomes in neutrophils and monocytes infiltrated in the mucosa in acid washing groups. According to the above results, it is concluded that E. coli lysate may easily penetrate into the bladder mucosa and that the mucosal mucopolysaccharide plays as a barrier against bacterial invasion.
Animals ; Cystitis ; Cytoplasm ; Cytoplasmic Vesicles ; Edema ; Estrogens, Conjugated (USP) ; Extracellular Space ; Immunohistochemistry ; Inflammation ; Lysosomes ; Mice ; Mice, Inbred ICR ; Microscopy ; Microscopy, Electron ; Monocytes ; Mucous Membrane* ; Necrosis ; Neutrophils ; Urinary Bladder*

Important progress has been made in the interpretation of subcellular location, ion transport characteristics and biological functions of endosomal Na⁺,K⁺/H⁺ antiporter in Arabidopsis thaliana. The endosomal Na⁺,K⁺/H⁺ antiporter contain two members, AtNHX5 and AtNHX6, whose amino acid sequence similarity is 78.7%. Studies have shown that AtNHX5 and AtNHX6 are functionally redundant, and they are all located in Golgi, trans-Golgi network (TGN), endoplasmic reticulum (ER) and prevacuolar compartment (PVC). AtNHX5 and AtNHX6 are critical for salt tolerance stress and the homeostasis of pH and K⁺. It has been reported that there are conservative acidic amino acid residues that can regulate their ion activity in the endosomal NHXs transmembrane domain, which plays a decisive role in their own functions. The results of the latest research indicate that endosomal NHXs affect vacuolar transport and protein storage, and participate in the growth of auxin-mediated development in A. thaliana. In this paper, the progress of subcellular localization, ion transport, function and application of endosomal NHXs in A. thaliana was summarized.
Arabidopsis ; Arabidopsis Proteins ; Endosomes ; Sodium-Hydrogen Exchangers ; Vacuoles

OBJECTIVE: To evaluate the change of cell surface CXC chemokine receptor 4 (CXCR4) expression of stem cells from apical papilla (SCAP) after the inhibition of endocytotic pathway, thus to provide experimental basis for the mechanism of SCAP migration. METHODS: The immunofluorescence analysis was conducted to examine the co-expression of CXCR4 and endocytotic compartments, including early endosomes, recycling endosomes and lysosomes in SCAP. Several Rab proteins were applied as markers of organelles in the endocytotic pathway, including Rab5 for early endosomes, Rab11A for recycling endosomes, and Lamp1 for lysosomes. The co-localization of CXCR4 with these endodontic compartments was further observed by proximity ligation assay (PLA). SCAP was treated with two kinds of endocytotic inhibitors, Blebbistatin and Dynasore, at a concentration of 80 μmol/L, respectively. The conditioning time was 1 hour. Flow cytometry was carried out to evaluate the proportion of SCAP that expressed CXCR4 on cell surface. The data were analysed by analysis of variance (ANOVA). RESULTS: The red staining of CXCR4 on immunofluorescence confocal microscopy predominantly overlapped with the green staining of Rab5 and Rab11A, and partly overlapped with Lamp1. It indicated that most CXCR4 molecules were located in early endosomes and recycling endosomes, and some were located in lysosomes. The PLA results revealed that the co-localizaiton of CXCR4 with endocytotic compartments could be observed in early endosomes, recycling endosomes and lysosomes. According to the results of flow cytometry, the proportion of SCAP that expressed CXCR4 on cell surface was as low as 0.13%±0.10%. After the inhibition of endocytosis by pretreating the cells with the following two inhibitors, Blebbistatin and Dynasore, the percentage of SCAP that positively expressed CXCR4 on cell surface was significantly increased to 13.34%±1.31% in Blebbistatin group and 4.03%±0.92% in Dynasore group (F=16.721, P<0.001). Moreover, the number of SCAP that expressed CXCR4 on cell surface in Blebbistatin group was significantly higher than that in Dynasore group (P<0.001). CONCLUSION The inhibition of endocytotic pathway could increase the number of SCAP that expressed CXCR4 on cell surface, and provide potency for the migration of SCAP.
Endocytosis ; Endosomes ; Lysosomes ; Receptors, CXCR4 ; Stem Cells

Microvesicles transport special proteins, micro RNA and DNA segments, which provides new access to intercellular communication. Tumor-derived membrane microvesicles (TMV) are involved in the tumor progress by transporting tumor-derived proteins, delivering microRNA to surrounding normal cells to alter their phenotype and promoting reverse transcription to interfere gene stability and to create tumor microenvironment. TMV also play crucial roles in tumor angiogenesis and matrix degradation, which facilitates malignant cell metastasis. TMVs are also involved in escaping immunological surveillance by intensifying the function of suppressor T cell and inducing apoptosis of cytotoxic T cells. On the other hand, microvesicles carry tumor antigens and can be used for development of tumor vaccines; some new vaccines such as AEX and DEX are under early clinical trials. Circulating microRNA and DNA segments in body fluid can be a new potential biomarker for cancer diagnosis and prognosis. Purification of microvesicles needs to be further improved, which is important for identification of microvesicles and their subtypes.
Cell Communication ; Cytoplasmic Vesicles ; chemistry ; physiology ; ultrastructure ; Humans ; Neoplasms ; pathology ; physiopathology ; Neoplastic Processes ; Neovascularization, Pathologic ; Tumor Microenvironment

The kinesin proteins (KIFs) make up a large superfamily of molecular motors that transport cargo such as vesicles, protein complexes, and organelles. KIF1A is a monomeric motor that conveys synaptic vesicle precursors and plays an important role in neuronal function. Here, we used the yeast two-hybrid system to identify the neuronal protein (s) that interacts with the tail region of KIF1A and found a specific interaction with synaptotagmin XI. The amino acid residues between 830 and 1300 of KIF1A are required for the interaction with synaptotagmin XI. KIF1A also bound to the tail region of synaptotagmin IV but not to other synaptotagmin in the yeast two-hybrid assay. KIF1A interacted with GST-synaptotagim XI fusion proteins, but not with GST alone. An antibody to synaptotagmin XI specifically co-mmunoprecipitated KIF1A associated with synaptotagimin from mouse brain extracts. These results suggest that KIF1A motor protein transports of synaptotagmin XI-containing synaptic vesicle precursors along microtubule.
Animals ; Brain ; Kinesin* ; Mice ; Microtubules ; Neurons ; Organelles ; Protein Transport ; Synaptic Vesicles ; Synaptotagmins* ; Two-Hybrid System Techniques